Tennis chiefs have been accused of failing to heed warnings of widespread match-fixing at the top level of the game, according to an investigation carried out by the BBC and BuzzFeed.

The media organisations claim to have uncovered evidence that the names of 16 players ranked in the world top 50 over the last decade were referred to the Tennis Integrity Unit due to suspicious activity.

They say the referrals were made as a result of an investigation which started in 2007 following an inquiry into suspicious betting patterns in a match between Nikolay Davydenko and Martin Vassallo Arguello, of which both men were acquitted.

Despite an increasing amount of evidence of suspicious activity revolving around a significant number of top players, no sanctions were handed out and the investigation was officially shelved the following year.

The allegations reportedly involve matches at Wimbledon and the French Open, and name numerous grand slam singles and doubles champions among the core group of suspects.

One of the betting investigators told the BBC he was astonished that the findings of the original 2007 inquiry were not followed up and acted upon by the relevant authorities.

Mark Phillips told the BBC: "Evidence that we gathered... we believed was very strong. There was a group of between six and 10 players really who were the main focus of the evidence that we dug up.

"We believed they (the TIU) would carry on the investigations from where we had taken them; we had done a lot of work on the investigation and certainly the betting investigations were a long way down the road.

"As far as we know, nothing happened with the evidence that we presented. Certainly none of the players that we had concerns about faced disciplinary action from the TIU in the next year or two."

However, ATP president Chris Kermode strongly denied that the TIU, which was set up as an independent body by the sport's various governing bodies, was deliberately seeking to hide any suspected improprieties.

Kermode went on to say he believed the threat of match-fixing in the sport remained at an "incredibly small level".

"It is simply not true that we are sitting on evidence," Kermode told the BBC.

"What happens is that information and intelligence are given to the Tennis Integrity Unit and they then have to turn that into evidence.

"There is a big difference here between information and intelligence as to evidence. Every single bit of information that the Tennis Integrity Unit receives is investigated properly.

"We take this so seriously. Their (the TIU's) job is to eradicate any of this going on. We are aware that it is there. I think that it is on an incredibly small level, and it is our business going forward that we keep acting upon this in the best possible way."

World number two Andy Murray on Sunday evening tweeted a link to the Buzzfeed report.

Building on the initial dossier of evidence, Buzzfeed News claims to have devised an algorithm which analysed gambling on professional tennis matches over the last seven years.

The organisation said its results identified 15 players who regularly featured in matches involving unusually lopsided betting patterns, and furthermore four of those players lost almost all of those matches concerned, at a probability of around 1,000 to one.